Commonly owned U.S. Pat. Nos. 4,850,319, 4,855,660, and 4,869,220 are applicable to an electronic throttle control for an I.C. engine powered automotive vehicle. Basically, an electronic throttle control comprises an electromechanical system replacing the heretofore strictly mechanical operative coupling via which the vehicle driver operates the engine throttle. A sensor associated with the vehicle's accelerator pedal provides an electric signal input to an electronic control unit which operates an electric motor to position the throttle in accordance with the driver's command.
While significant advantages can be derived from the incorporation of an electronic throttle control into an I.C. engine powered automotive vehicle, as seen in the referenced commonly owned patents, the well-known conservative philosophies of automobile manufacturing companies are barriers to the adoption of other than cosmetic changes to their products. Since domestic manufacturers are viewed in some quarters as pleasantly enjoying a shared monopoly, the sole incentives for substantive improvements in their products are seen by some to consist only of those which are either coerced by government fiat or else calculated by the manufacturers to handsomely increase their profits. Since the manufacture of automotive vehicles has historically developed as a smokestack industry, it is not an unduly unfair observation to say that the industry harbors an innate resistance to, perhaps approaching the point of fear of, the introduction of modern electronic technology into its products. Accordingly, an independent electronics company that pioneers the development of new electronic technology for automotive vehicle applications must be highly innovative and creative in order for that technology to have any chance for acceptance by automotive manufacturers where either essential compliance with government regulations or immediate profit returns otherwise hold sway.
The present invention relates to an improvement for furthering acceptance of an electronic throttle control by an automotive manufacturer. More specifically the invention relates to a novel means for assuring correspondence of motorized throttle operation to that which is intended by the actions of the vehicle operator and for rendering suitable contingency action in the unlikely event that correspondence becomes unacceptably disparate. One of the especially unique aspects of the invention resides in its relative simplicity, for its principles can be embodied in a what is essentially a single electrical circuit portion of an electronic throttle control system.
Described in one manner, the invention comprises a means for selectively allowing or disallowing continuance of engine operation depending upon the driver's use of the accelerator and the brakes, and the throttle position that results from the actions of the driver. Engine operation is allowed to continue as long as the throttle attains at least a certain degree of engine throttling within a certain time limit after the concurrence of signals indicating that the accelerator has been released and that the brakes have been applied. Non-attainment of such a condition disallows continuance of engine operation.
Principles of the invention will be disclosed in the ensuing detailed description of a presently preferred embodiment and in the accompanying claims. Drawings also accompany the disclosure and illustrate the presently preferred embodiment in the best mode contemplated by the inventors for putting the invention into practice.